The invention relates to a sliding plate valve of the type used in the gas industry, for example.
Sliding plate valves are extensively used to provide a low profile mechanism to isolate main pipes for gas and water. In addition they can be used as an entry point for mains inspection for the passage of a camera, for example, through the pipe. Where a tow line or camera signal cable is to move through a pipeline, it is necessary, where fluid under pressure is still present in the pipeline, to provide such access for such cables under sealed conditions.
A sliding plate valve suitable for such situations as disclosed in UK patent number GB 2 261 277 which employs a notch and seal arrangement to trap such a cable while sealing the pipe by means of the plate valve. The present invention is concerned with providing improvements over such a configuration.
According to the invention there is provided a plate valve having a bore for passage of a fluid; a sliding plate for closing the bore, a first recessed seal portion on the valve body extending from the bore and a second recessed seal portion on the sliding plate adapted to cooperate with a cable or the like to effect a seal with the cable and the first seal portion on closure of the plate. In a preferred embodiment two slide plates are provided each with an associated first and second recessed seal portion.
The plate valve may include an incorporated equalisation valve.
The invention will now be described by way of example according to the accompanying drawings in which: